Laterally diffused metal oxide semiconductor device integrated with vertical field effect transistor

ABSTRACT

An electrical device that in some embodiments includes a substrate including a lateral device region and a vertical device region. A lateral diffusion metal oxide semiconductor (LDMOS) device may be present in the lateral device region, wherein a drift region of the LDMOS device has a length that is parallel to an upper surface of the substrate in which the LDMOS device is formed. A vertical field effect transistor (VFET) device may be present in the vertical device region, wherein a vertical channel of the VFET has a length that is perpendicular to said upper surface of the substrate, the VFET including a gate structure that is positioned around the vertical channel.

BACKGROUND Technical Field

The present disclosure relates to methods of forming semiconductordevices and the electronic device structures produced thereby, and moreparticularly to a method of epitaxially forming the drain, channel, andsource of a vertical finFET.

Description of the Related Art

A Field Effect Transistor (FET) typically has a source, a channel, and adrain, where current flows from the source to the drain, and a gate thatcontrols the flow of current through the channel. The dimensions ofsemiconductor field effect transistors (FETs) have been steadilyshrinking over the last thirty years or so, as scaling to smallerdimensions leads to continuing device performance improvements. PlanarFET devices typically have a conducting gate electrode positioned abovea semiconducting channel, and electrically isolated from the channel bya thin layer of gate oxide. Current through the channel is controlled byapplying voltage to the conducting gate. With conventional planar FETscaling reaching fundamental limits, the semiconductor industry islooking at more unconventional geometries that will facilitate continueddevice performance improvements.

SUMMARY

In one aspect, the present disclosure provides an electrical device thatincludes a substrate including a lateral device region and a verticaldevice region. A first semiconductor device in the lateral deviceregion, wherein a lateral channel region of the first semiconductordevice has a length that is parallel to an upper surface of thesubstrate in which the first semiconductor device is formed. A secondsemiconductor device is present in the vertical device region, wherein avertical channel has a length that is perpendicular to said uppersurface of the substrate, the second semiconductor device including agate structure that is positioned around the vertical channel.

In another embodiment, the electrical device includes a substrateincluding a lateral device region and a vertical device region. Alateral diffusion metal oxide semiconductor (LDMOS) device is present inthe lateral device region, wherein a diffusion region of the LDMOSdevice has a length that is parallel to an upper surface of thesubstrate in which the LDMOS device is formed. A vertical field effecttransistor (VFET) device is present in the vertical device region,wherein a vertical channel of the VFET has a length that isperpendicular to said upper surface of the substrate, the VFET includinga gate structure that is positioned around the vertical channel.

In yet another aspect of the present disclosure, a method of forming anelectrical device is provided. In one embodiment, the method includesforming at least one first fin structure in a lateral device region of asubstrate and forming at least one second fin structure in a verticaldevice region of the substrate. A drift region is formed in the lateraldevice region and a dopant region is formed in the vertical deviceregion of the substrate for the first of a source region and drainregion. A dielectric layer is formed in the lateral device region of thesubstrate and the vertical device region of the substrate. A firstportion of the dielectric layer provides a gate dielectric for a LDMOSdevice being formed in the lateral device region. A second portion ofthe dielectric spacer provides a spacer for the VFET. A gate structureis formed for the LDMOS devices and the VFET devices. An epitaxialsemiconductor material is formed on the at least one first fin structurein the lateral device region of the substrate and the at least onesecond fin structure in the vertical device region of the substrate. Theepitaxial semiconductor material in the lateral device region mayprovide dopant region for one of source region or drain region for theLDMOS device. The epitaxial semiconductor material in the verticaldevice region provides a doped region for a second of the source regionand drain region.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The disclosure will provide details in the following description ofpreferred embodiments with reference to the following figures wherein:

FIG. 1 is a side cross-sectional view of a substrate that has beenetched to provide at least one first fin structure in a lateral deviceregion and at least one second fin structure in a vertical deviceregion, in accordance with one embodiment of the present disclosure.

FIG. 2 is a side cross-sectional view of forming at least one conformaldielectric layer on the fin structures, and forming isolation regionsseparating the lateral device region from the vertical device region, inaccordance with one embodiment of the present disclosure.

FIG. 3 is a side cross-sectional view depicting one embodiment offorming a drift region in the lateral device region of the substrate, inaccordance with the present disclosure.

FIG. 4 is a side cross-sectional view depicting one embodiment offorming a first of a source region and a drain region in the verticaldevice region of the substrate, in accordance with one embodiment of thepresent disclosure.

FIG. 5 is a side cross-sectional view depicting one embodiment offorming a dielectric layer in the lateral device region of the substrateand the vertical device region of the substrate, wherein a first portionof the dielectric layer provides a drift region gate dielectric for aLDMOS device being formed in the lateral device region, and a secondportion of the dielectric spacer provides a spacer for the VFET beingformed in the vertical device region.

FIG. 6 is a side cross-sectional view of forming a thickened portion ofthe dielectric layer in the lateral device region, in accordance withone embodiment of the present disclosure.

FIG. 7 is a side cross-sectional view depicting one embodiment offorming a gate dielectric on the fin structures, in accordance with thepresent disclosure.

FIG. 8 is a side cross-sectional view depicting forming the materiallayers for the gate structures for the LDMOS devices and the VFETdevices, in accordance with one embodiment of the present disclosure.

FIG. 9 is a side cross-sectional view depicting patterning the materiallayer for the gate structures for the LDMOS devices and the VFETdevices, in accordance with one embodiment of the present disclosure.

FIG. 10 is a side cross-sectional view depicting forming an epitaxialsemiconductor material on the at least one first fin structure in thelateral device region of the substrate and the at least one second finstructure in the vertical device region of the substrate, in accordancewith the present disclosure.

FIG. 11A is a top down view of an LDMOS semiconductor device inaccordance with one embodiment of the present disclosure.

FIG. 11B is a side cross-sectional view of one embodiment of an LDMOSsemiconductor device, as depicted in FIG. 11A, in which the drift oxidehas a single thickness.

FIG. 11C is a side cross-sectional view of another embodiment of anLDMOS semiconductor device, as depicted in FIG. 11A, in which the driftoxide has two drift oxide thicknesses.

FIG. 12A is a top down view of an LDMOS semiconductor device having arectangular contact to the gate region, in accordance with oneembodiment of the present disclosure.

FIG. 12B is a side cross-sectional view of the LDMOS semiconductordevice depicted in FIG. 12A.

FIG. 13A is a top down view of a split gate LDMOS semiconductor device.

FIG. 13B is a side cross-sectional view of the LDMOS semiconductordevice depicted in FIG. 13A.

FIG. 14A is a top down view of a symmetrical LDMOS semiconductor device,in accordance with some embodiments of the present disclosure.

FIG. 14B is a side cross-sectional view of the structure depicted inFIG. 14A, in which the LDMOS device includes two source contacts.

FIG. 14C is a side cross-sectional view of the structure depicted inFIG. 14A, in which the LDMOS device includes a single source contact.

FIG. 15A is a top down view of a LDMOS semiconductor device including anisolation region in the drift region, in accordance with someembodiments of the present disclosure.

FIG. 15B is a side cross-sectional view of the structure depicted inFIG. 15A.

FIG. 16A is a top down view of another embodiment of an LDMOSsemiconductor device including an isolation region in the drift region,in which the gate contact is offset from the source contact and thediffusion region contact, in accordance with one embodiment of thepresent disclosure.

FIG. 16B is a side cross-sectional view of the structure depicted inFIG. 16A.

DETAILED DESCRIPTION

Detailed embodiments of the claimed structures and methods are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely illustrative of the claimed structures and methods that maybe embodied in various forms. In addition, each of the examples given inconnection with the various embodiments is intended to be illustrative,and not restrictive. Further, the figures are not necessarily to scale,some features may be exaggerated to show details of particularcomponents. Therefore, specific structural and functional detailsdisclosed herein are not to be interpreted as limiting, but merely as arepresentative basis for teaching one skilled in the art to variouslyemploy the methods and structures of the present disclosure. Forpurposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, andderivatives thereof shall relate to the embodiments of the disclosure,as it is oriented in the drawing figures. The terms “positioned on”means that a first element, such as a first structure, is present on asecond element, such as a second structure, wherein interveningelements, such as an interface structure, e.g. interface layer, may bepresent between the first element and the second element. The term“direct contact” means that a first element, such as a first structure,and a second element, such as a second structure, are connected withoutany intermediary conducting, insulating or semiconductor layers at theinterface of the two elements.

In some embodiments, the methods and structures disclosed herein form aVertical Fin Field Effect Transistor (VFET) in combination with aLateral Diffusion Metal Oxide Semiconductor (LDMOS) device on the samesemiconductor substrate. A field effect transistor (FET) is asemiconductor device in which output current, i.e., source-draincurrent, is controlled by the voltage applied to a gate structure to thesemiconductor device. A field effect transistor has three terminals,i.e., gate structure, source region and drain region. As used herein, a“fin structure” refers to a semiconductor material, which is employed asthe body of a semiconductor device, in which the gate structure ispositioned around the fin structure such that charge flows down thechannel of the fin structure A finFET is a semiconductor device thatpositions the channel region of the semiconductor device in a finstructure. The source and drain regions of the fin structure are theportions of the fin structure that are on opposing sides of the channelregion of the fin structure.

In an embodiment, a finFET semiconductor device has the drain, finchannel, and source device components arranged perpendicular to theplane of the substrate surface, which is referred to as a verticalstack. A vertically stacked finFET, i.e., Vertical FinFET (VFinFET), canhave a longer gate length (i.e., height) and larger dielectric spacerthan a horizontal (i.e., having the drain, fin channel, and sourcedevice components arranged parallel with the plane of the substratesurface) finFET having comparable contact gate pitch.

The Laterally Diffused MOSFET (LDMOS) is an asymmetric power MOSFET thatin some examples can be designed for low on-resistance and high blockingvoltage. These features can be obtained by creating a diffused firstconductivity type channel region, e.g., p-type channel region, in alow-doped second conductivity type drain region, e.g., n-type drainregion. The low doping on the drain side results in a large depletionlayer with high blocking voltage. In some examples, the channel regiondiffusion can be defined with the same mask as the source region,resulting in a short channel with high current handling capability. TheLDMOS structure combines a short channel length with high breakdownvoltage as desired for high power RF amplifiers, e.g., ranging from 10MHz to 3.8 GHz, in numerous applications. This device is currently thedevice of choice for RF power amplifiers in base stations of wirelesscommunications systems as well as numerous UHF and L-band poweramplifiers in broadcast, communication and radar systems. The methodsand structures disclosed herein integrate LDMOS devices with VFETs. Themethods and structures of the present disclosure are now described withgreater detail with reference to FIGS. 1-16B.

FIG. 1 depicts one embodiment of a substrate 1 that has been etched toprovide at least one first fin structure 5 in a lateral device region15, and at least one second fin structure 10 in a vertical device region20 of the substrate 1. In various embodiments, the substrate 1 may be asemiconductor. The substrate 1 may be crystalline. The substrate 1 maybe primarily (i.e., with doping) of a single element, for example,silicon (Si) or germanium, (Ge), or the substrate 1 may be a compound,for example, GaAs, SiC, or SiGe. The substrate 1 may also have multiplematerial layers, for example, a semiconductor-on-insulator substrate(SeOI), a silicon-on-insulator substrate (SOI), germanium-on-insulatorsubstrate (GeOI), or silicon-germanium-on-insulator substrate (SGOI).The substrate 1 may also have other layers forming the substrate,including high-k oxides and/or nitrides. In one or more embodiments, thesubstrate 1 may be a silicon wafer. In an embodiment, the substrate is asingle crystal silicon wafer.

The substrate 1 includes a first device region, also referred to aslateral device region 15, in which the LDMOS device is to be formed, anda second device region, also referred to as a vertical device region 20,in which the VFET is to be formed.

The substrate 1 may be processed to provide fin structures 5, 10. Thefin structures 5, 10 are typically formed using deposition,photolithography, i.e., patterning, and etch processes. In oneembodiment, the patterning process used to define each of the finstructures 5, 10 is a sidewall image transfer (SIT) process. The SITprocess can include forming a first mandrel material layer (not shown)on the material layer that provides the fin structures 5, 10. The firstmandrel material layer can include any material (semiconductor,dielectric or conductive) that can be selectively removed from thestructure during a subsequently performed etching process. The firstmandrel material layer can be formed by a deposition method, such aschemical vapor deposition or plasma enhanced chemical vapor deposition.In one embodiment, the thickness of the first mandrel material layer canbe from 50 nm to 300 nm. Following deposition of the first mandrelmaterial layer, the first mandrel material layer can be patterned bylithography and etching to form a plurality of first mandrel structureson the topmost surface of the semiconductor containing material thatprovides the fin structures 10, e.g., the upper surface of thesemiconductor substrate 1.

In some embodiments, the SIT process may continue by forming adielectric spacer on each sidewall of each of the first mandrelstructures. The dielectric spacer can be formed by deposition of adielectric spacer material, and then etching the deposited dielectricspacer material. The dielectric spacer material may comprise anydielectric spacer material such as, for example, silicon dioxide,silicon nitride or a dielectric metal oxide. Examples of depositionprocesses that can be used in providing the dielectric spacer materialinclude, but are not limited to, chemical vapor deposition (CVD), plasmaenhanced chemical vapor deposition (PECVD), or atomic layer deposition(ALD). Examples of etching that be used in providing the dielectricspacers include any etching process such as, e.g., reactive ion etching(RIE). Since the dielectric spacers are used in the SIT process as anetch mask, the width of the each dielectric spacer determines the widthof each fin structure 5, 10.

In some embodiments, after formation of the dielectric spacers, the SITprocess continues by removing each the first mandrel structure. Each ofthe first mandrel structures can be removed by an etching process thatis selective for removing the mandrel material as compared tosemiconductor material of the substrate that provides the fin structures5, 10, e.g., silicon (Si). Following the first mandrel structureremoval, the SIT process continues by transferring the pattern providedby the dielectric spacers into the semiconductor material layer thatprovides the fin structures 5, 10, such as the upper surface ofsemiconductor substrate 1. The pattern transfer may be achieved byutilizing at least one etching process that can include dry etching,such as reactive ion etching (RIE), plasma etching, ion beam etching orlaser ablation, chemical wet etch processes or a combination thereof. Inone example, the etch process used to transfer the pattern may includeone or more reactive ion etching (RIE) steps. The etching steps patternthe semiconductor substrate 1 to provide the fin structures 10, 15.Following etching, i.e., pattern transfer, the SIT process may concludewith removing the dielectric spacers using an etch process or aplanarization process.

It is noted that the aforementioned spacer image transfer (SIT) processis only one method of forming the fin structures 5, 10. In anotherembodiment, each of the fin structures 5, 10 may be formed using aphotoresist etch mask. Specifically, in one example, a photoresist maskis formed overlying the semiconductor composition layer which providesthe fin structures 5, 10. The exposed portions of the semiconductorlayer that provides the fin structures 5, 10 that are not protected bythe photoresist mask are removed using a selective etch process. Toprovide the photoresist mask, a photoresist layer is first positioned onthe portion of the semiconductor substrate 1 that provides the finstructures 5, 10. The photoresist layer may be provided by a blanketlayer of photoresist material that is formed utilizing a depositionprocess such as, e.g., plasma enhanced CVD (PECVD), evaporation orspin-on coating.

The blanket layer of photoresist material is then patterned to providethe photoresist mask utilizing a lithographic process that may includeexposing the photoresist material to a pattern of radiation anddeveloping the exposed photoresist material utilizing a resistdeveloper. Following the formation of the photoresist mask, an etchingprocess may remove the unprotected portions of the semiconductorsubstrate 1 that provides the fin structures 5, 10, e.g., selectivelyetch the unprotected portions. The etch process may be an anisotropicprocess, such as reactive ion etch (RIE).

In some embodiments, each of the fin structures 5, 10 may have a heightH1 ranging from 5 nm to 200 nm. In another embodiment, each of theplurality of fin structures 5, 10 has a height H1 ranging from 10 nm to100 nm. In one example, each of the plurality of fin structures 10 has aheight H1 ranging from 20 nm to 50 nm. Each of the plurality of finstructures 10 may have a width W1 of less than 20 nm. In anotherembodiment, each of the plurality of fin structures 10 has a width W1ranging from 3 nm to 15 nm.

Although one fin structure is depicted in the lateral device region 15,and three fin structures are depicted in the vertical device region 20that is depicted in FIG. 1, the present disclosure is not limited toonly this example. It is noted that any number of fin structures 5, 10may be present in the lateral device region 15 and the vertical deviceregion 20 of the substrate 1. The pitch P1 separating adjacent finstructures 10 in the vertical device region 20 may range from 15 nm to500 nm. In another example, the pitch P1 separating adjacent finstructures 10 in the vertical device region 20 may range from 20 nm to50 nm.

The fin structure 10 may be composed of a type IV semiconductor materialor a compound semiconductor material. By “type IV semiconductor” it ismeant that the semiconductor material includes at least one element fromGroup IVA (i.e., Group 14) of the Periodic Table of Elements. Examplesof type IV semiconductor materials that are suitable for the finstructure include silicon (Si), germanium (Ge), silicon germanium(SiGe), silicon doped with carbon (Si:C), silicon germanium doped withcarbon (SiGe:C) and a combination thereof. Typically, the semiconductorsubstrate 5 is composed of silicon (Si), e.g., single crystal silicon.One example of a compound semiconductor composition that may provide thefin structures 10 is a type III-V semiconductor. Typically, the III-Vcompound semiconductors are binary, ternary or quaternary alloysincluding III/V elements. Examples of III-V compound semiconductors thatcan be used for the composition of the fin structures 5, 10 include, butare not limited to alloys of gallium arsenic (GaAs), aluminum arsenic(AlAs), indium gallium arsenic (InGaAs), indium aluminum arsenic(InAlAs), indium aluminum arsenic antimony (InAlAsSb), indium aluminumarsenic phosphorus (InAlAsP), indium gallium arsenic phosphorus(InGaAsP) and combinations thereof. Typically, the fin structures arenot doped with n-type or p-type dopant via external doping methods.

Still referring to FIG. 1, a dielectric cap 2 may be present atop eachof the fin structures 5, 10. The dielectric cap 2 may be composed of anoxide, nitride or oxynitride material, and may be formed as part of theprocess sequence that forms the fin structures 5, 10. For example, whenthe dielectric cap 2 is composed of an oxide, the oxide may be siliconoxide. For example, when the dielectric cap 2 is composed of a nitride,the nitride may be silicon nitride.

FIG. 2 depicts one embodiment of forming at least one conformaldielectric layer 3, 4 on the fin structures 5, 10, and forming isolationregions 6 separating the lateral device region 15 from the verticaldevice region 20. The term “conformal layer” denotes a layer having athickness that does not deviate from greater than or less than 30% of anaverage value for the thickness of the layer. In some examples, the atleast one conformal dielectric layer 3, 4 is a bilayer of an oxidecontaining layer 3 and a nitride containing layer 4. The oxidecontaining layer 3 may be blanket deposited atop the structure depictedin FIG. 1 including the fin structures 5, 10 and the upper surface ofthe semiconductor substrate that is separating the adjacent finstructures 5, 10. In one example, the oxide containing layer 5 may becomposed of silicon oxide. The nitride containing layer 4 may be blanketdeposited atop the oxide containing layer. In one example, the nitridecontaining layer 4 is composed of silicon nitride. To provide theconformal layer for the oxide containing layer 3 and the nitridecontaining layer 4, the at least one conformal dielectric layer 3, 4 maybe deposited using chemical vapor deposition (CVD) or atomic layerdeposition (ALD). In some embodiments, the thickness for each of theoxide containing layer 3 and the nitride containing layer 4 may rangefrom 0.5 nm to 15 nm. In other embodiments, the thickness for each ofthe oxide containing layer 3 and the nitride containing layer 4 mayrange from 1 nm to 5 nm.

Still referring to FIG. 2, isolation regions 6 may be formed separatingthe lateral device region 15 from the vertical device region 20. Formingthe isolation regions 6 may include forming a first dielectric layeratop the at least one conformal dielectric layer 3, 4, and planarizingthe first dielectric layer so that the upper surface of the firstdielectric layer is coplanar with the upper surface of the dielectriccap 2. The planarization process may be provided by chemical mechanicalplanarization (CMP). The first dielectric layer and the portions of thesubstrate 1 at the interface between the lateral device region 15 andthe vertical device region 20 may then be etched with a shallow trenchisolation region etch for forming a trench structure. The etch processmay including forming a photoresist mask and then applying ananisotropic etch, such as reactive ion etch (RIE), for forming thetrench structure. The trench structure may then be filled with aninsulating dielectric, such as silicon oxide, which may be depositedusing a chemical vapor deposition (CVD) process, such as plasma enhancedchemical vapor deposition.

FIG. 3 depicts one embodiment of forming a drift region 8 in the lateraldevice region 15 of the substrate 1. The drift region 8 is a componentof the LDMOS device is present in the portion of the substrate 1 withinthe lateral device region 15 between the isolation regions 6. The driftregion is typically doped with a conductivity type dopant that isopposite the conductivity type of the LDMOS device. The term“conductivity type” denotes whether the dopant provides a p-typeconductivity or an n-type conductivity. As used herein, “p-type” refersto the addition of impurities to an intrinsic semiconductor that createsdeficiencies of valence electrons. In a type IV semiconductor material,such as silicon and germanium, examples of p-type dopants, i.e.,impurities, include but are not limited to: boron, aluminum, gallium andindium. As used herein, “n-type” refers to the addition of impuritiesthat contributes free electrons to an intrinsic semiconductor. In a typeIV semiconductor material, such as silicon or germanium, examples ofn-type dopants, i.e., impurities, include but are not limited toantimony, arsenic and phosphorous.

For example, in one embodiment, in which the LDMOS device has an n-typeconductivity, the drift region 8 may be doped to a p-type conductivity.In another example, when the LDMOS device has a p-type conductivity, thedrift region 8 may be doped to an n-type conductivity.

Before forming the drift region 8, the first dielectric layer may berecessed to reveal the fin structures 5, 10. Recessing the firstdielectric layer can include a selective etch process, such as a wetchemical etch, or a dry etch, such as reactive ion etch (RIE). The etchprocess may be selective to the at least one conformal dielectric layer3, 4 that is present on the fin structures 5, 10.

To provide the drift region 8 in the lateral device region 15, a firstblock mask may be formed over the vertical device region 20, and thedopant that provides the selected conductivity type is implanted intothe exposed lateral device region 15. In some embodiments, the firstblock mask may be a photoresist mask that is formed usingphotolithography and development processes. In one embodiment, thedopant that provides the conductivity type may be doped into the portionof the semiconductor substrate 1 in which the drift region 8 is formedat a concentration ranging from 1×10¹¹ atoms/cm³ to 1×10¹³ atoms/cm³. Inanother embodiment, the dopant that provides the conductivity type maybe doped into the portion of the semiconductor substrate 1 in which thedrift region 8 is formed at a concentration ranging from 5×10¹¹atoms/cm³ to 5×10¹² atoms/cm³. In one example, the dopant that providesthe conductivity type may be doped into the portion of the semiconductorsubstrate 1 in which the drift region 8 is formed at a concentration of1×10¹² atoms/cm³.

Following ion implantation of the dopant for the drift region 8, thestructure is annealed. The anneal process may be provided by thermalanneal, such as rapid thermal anneal (RTA), laser annealing, IR heating,furnace annealing and combinations thereof. The anneal process forforming the drift region 8 may be at a temperature ranging from 800° C.to 1100° C. Following formation of the drift region 8, the first blockmask that was formed over the vertical device region 20 is removed.

FIG. 4 depicts one embodiment of forming a dopant region 9 for a firstof a source region and a drain region in the vertical device region 20of the substrate 1. By a first of the source region and the drainregion, it is meant that dopant region provides one of a source regionor a drain region, and the other of the source or drain region is formedon an opposing side of the fin structure 10. For example, when the dopedregion 9 is a source region, the drain region is formed on the opposingsurface, i.e., upper surface of the fin structure 10. In anotherexample, when the doped region is a drain region, the source region isformed on the opposing surface, i.e., upper surface of the fin structure10. Typically, the conductivity type for the doped region 9 dictates theconductivity type of the VFET. For example, when the doped region 9 isimplanted to an n-type conductivity, the VFETs are n-type semiconductordevices. For example, when the doped region 9 is implanted to a p-typeconductivity, the VFETs are p-type semiconductor devices.

To provide the dopant region 9 in the vertical device region 20, asecond block mask may be formed over the lateral device region 15, andthe dopant that provides the selected conductivity type for the VFETs isimplanted into the exposed vertical device region 20. In someembodiments, the second block mask may be a photoresist mask that isformed using photolithography and development processes. In oneembodiment, the dopant that provides the conductivity type for the VFETsmay be doped into the portion of the semiconductor substrate 1 betweenthe fin structures 10 to provide the doped region 9 for a first of asource region and a drain region at a concentration ranging from 5×10¹⁹atoms/cm³ to 5×10²¹ atoms/cm³. In another embodiment, the dopant thatprovides the conductivity type for the VFETs may be doped into theportion of the semiconductor substrate 1 between the fin structures 10to provide the doped region 9 for a first of a source region and a drainregion at a concentration ranging from 5×10¹⁹ atoms/cm³ to 5×10²⁰atoms/cm³.

Following ion implantation of the dopant for the doped region 9 for afirst of a source region and a drain region, the structure is annealedto provide a diffused dopant region 9′. The anneal process may beprovided by thermal anneal, such as rapid thermal anneal (RTA), laserannealing, IR heating, furnace annealing and combinations thereof. Theanneal process for forming the doped region 9 may be at a temperatureranging from 800° C. to 1100° C. Following formation of the doped region9, the block mask that was formed over the lateral device region 15 isremoved.

FIG. 5 depicts one embodiment of forming a dielectric layer 11A, 11B inthe lateral device region 15 of the substrate 1 and the vertical deviceregion 20 of the substrate 1, wherein a first portion of the dielectriclayer 11A provides a drift region gate dielectric for a LDMOS devicebeing formed in the lateral device region 15, and a second portion ofthe dielectric layer 11B provides a spacer for the VFET being formed inthe vertical device region 20.

In some embodiments, before the dielectric layer 11A, 11B is deposited,the at least one conformal dielectric layer 3, 4 may be removed from theupper surfaces of the portions of the substrate separating the finstructures 5, 10. The at least one conformal dielectric layer 3, 4 maybe removed using an etch process that is selective to the fin structures5, 10 and the substrate 1. In some embodiments, the lateral portions ofthe at least one conformal dielectric layer 3, 4, i.e., the portions ofthe conformal dielectric layer 3, 4 that are present on the uppersurfaces of the substrate 1 and the upper surface of dielectric cap 2overlying the fin structures 5, 10 is removed by an anisotropic etch,such as reactive ion etch (RIE).

The dielectric layer 11A, 11B may be an oxide or a nitride dielectriclayer. For example, the dielectric layer 11A, 11B may be composed ofsilicon oxide. In other examples, the dielectric layer 11A, 11B may becomposed of a nitride, such as silicon nitride. In yet otherembodiments, the dielectric layer 11A, 11B may be composed of a high-kdielectric material. As used herein, “high-k” denotes a dielectricmaterial featuring a dielectric constant (k) higher than the dielectricconstant of SiO₂ at room temperature. For example, the dielectric layer11A, 11B may be composed of a high-k oxide such as, for example, HfO₂,ZrO₂, Al₂O₃, TiO₂, La₂O₃, SrTiO₃, LaAlO₃, Y₂O₃ and mixtures thereof.Other examples of high-k dielectric materials for the at least one gatedielectric include hafnium silicate, hafnium silicon oxynitride orcombinations thereof.

The dielectric layer 11A, 11B may be formed using a deposition process,such as chemical vapor deposition (CVD) or atomic layer deposition(ALD), or may be formed using a growth process, such as thermaloxidation. The dielectric layer 11A, 11B, may have a thickness rangingfrom 2 nm to 20 nm. In some examples, the dielectric layer 11A, 11B mayhave a thickness ranging from 2 nm to 10 nm.

[[Normally the Thick Oxide is Formed First and then the Thin (CriticalOxide) is Formed on Top of the Thick.]]

FIG. 6 depicts one embodiment of an optional step of increasing thethickness of a portion of the dielectric layer 11A that is present inthe lateral device region 10, wherein the thickness of the dielectriclayer 11A is being increased for applications in higher voltages. Insome embodiments, the portion of the dielectric layer 11C having thegreater thickness does not extend across the entire portion of thedielectric layer 11A that is present in the lateral device region 10.The portion of the dielectric layer 11C having the greater thickness maybe selectively formed by using a block mask, e.g., a photoresist mask,that is covering the portions of the structure depicted in FIG. 5 inwhich additional dielectric deposition is not desired. The block maskhas an opening exposing the portion of the dielectric layer 11A on whichaddition dielectric material is to be formed producing the greaterthickness dielectric layer 11A. The greater thickness dielectric layer11C typically has the same composition as the dielectric layer 11A thatis present in the lateral device region 10. The greater thicknessdielectric layer 11C is typically formed using thermal growth or adeposition process, such as chemical vapor deposition (CVD) or atomiclayer deposition (ALD). The greater thickness dielectric layer 11C mayhave a thickness ranging from 5 nm to 25 nm. In other embodiments, thethickness of the greater thickness dielectric layer 11C may range from 6nm to 12 nm. It is noted that the process step depicted in FIG. 6, aswell as the resulting greater thickness dielectric layer 11C, isoptional and may be omitted. Further, although FIGS. 7-10 illustrate aprocess that does not employ the optional steps and structures depictedin FIG. 6, the methods and structures depicted in FIGS. 7-10 are equallyapplicable to the embodiments including the optional method steps andstructures that are depicted in FIG. 6.

FIG. 7 depicts one embodiment of forming a gate dielectric 12 on the finstructures 5, 10. Forming the gate dielectric 12 may include removing atleast a portion of the at least one conformal dielectric layer 3, 4. Theat least one conformal dielectric layer 3, 4 may be removed by an etchprocess. For example, the at least one conformal dielectric layer 3, 4may be removed by an etch that is selective to the fin structure 5, 10and the dielectric layer 11A, 11B, 11C (when present). The etch processmay be a wet chemical etch, or a dry etch, such as reactive ion etch(RIE).

In a following process step, the gate dielectric 12 may be formed on thefin structures, as well as the dielectric layer 11A, 11B, 11C (whenpresent). Typically, the gate dielectric is formed using a conformaldeposition process. The gate dielectric may be composed of anydielectric material, such as an oxide, nitride or oxynitride material.In some embodiments, the gate dielectric is a high-k dielectricmaterial. For example, the least one gate dielectric layer may becomposed of a high-k oxide such as, for example, HfO₂, ZrO₂, Al₂O₃,TiO₂, La₂O₃, SrTiO₃, LaAlO₃, Y₂O₃ and mixtures thereof. Other examplesof high-k dielectric materials for the at least one gate dielectricinclude hafnium silicate, hafnium silicon oxynitride or combinationsthereof.

To provide the conformal layer, the gate dielectric 12 may be depositedusing atomic layer deposition (ALD). In other embodiments, the gatedielectric 12 may be deposited using chemical vapor deposition methods,such as plasma enhanced chemical vapor deposition (PECVD). In oneembodiment, the thickness of the at least one gate dielectric layer 12is greater than 0.8 nm. More typically, the at least one gate dielectriclayer 12 has a thickness ranging from about 1.0 nm to about 6.0 nm.

In some embodiments, conformal deposition of the gate dielectric 12produces a vertical gate dielectric on the channel portion of the finstructures 10 in the vertical device region 20 for the VFETs. In someembodiments, the conformal deposition of the gate dielectric 12 producesa vertical portion of the gate dielectric that is present on the finstructure 5 and leads to a lateral portion of the gate dielectric forthe LDMOS that is provided by the dielectric layer 11A overlying thedrift region 8.

FIG. 8 depicts forming the material layers for the gate conductors 14for the LDMOS devices and the VFET devices. In some embodiments, thematerial layers for the gate conductors 14 may include a work functionmetal. The work function metal may be selected to provide a p-type workfunction metal layer and an n-type work function metal layer. As usedherein, a “p-type work function metal layer” is a metal layer thateffectuates a p-type threshold voltage shift. In one embodiment, thework function of the p-type work function metal layer ranges from 4.9 eVto 5.2 eV. As used herein, “threshold voltage” is the lowest attainablegate voltage that will turn on a semiconductor device, e.g., transistor,by making the channel of the device conductive. The term “p-typethreshold voltage shift” as used herein means a shift in the Fermienergy of a p-type semiconductor device towards a valence band ofsilicon in the silicon containing substrate of the p-type semiconductordevice. A “valence band” is the highest range of electron energies whereelectrons are normally present at absolute zero. In one embodiment, thep-type work function metal layer may be composed of titanium and theirnitrided/carbide. In one embodiment, the p-type work function metallayer is composed of titanium nitride (TiN). The p-type work functionmetal layer may also be composed of TiAlN, Ru, Pt, Mo, Co and alloys andcombinations thereof.

As used herein, an “n-type work function metal layer” is a metal layerthat effectuates an n-type threshold voltage shift. “N-type thresholdvoltage shift” as used herein means a shift in the Fermi energy of ann-type semiconductor device towards a conduction band of silicon in asilicon-containing substrate of the n-type semiconductor device. The“conduction band” is the lowest lying electron energy band of the dopedmaterial that is not completely filled with electrons. In oneembodiment, the work function of the n-type work function metal layerranges from 4.1 eV to 4.3 eV. In one embodiment, the n-type workfunction metal layer is composed of at least one of TiAl, TaN, TiN, HfN,HfSi, or combinations thereof.

The material layers for the gate conductors 14 for the LDMOS devices andthe VFET devices may also include a metal, such as tungsten (W),tungsten nitride (WN) or combinations thereof.

The material layers for the gate conductors 14 for the LDMOS devices andthe VFET devices may be deposited by PVD, CVD or PE-CVD. The PVD methodsfor forming the gate conductors 14 may include plating, electroplating,electroless plating, sputtering and combinations thereof. In someembodiments, following deposition the material layers for the gateconductor 14 may be recessed to a desired gate height using an etchprocess. This etch step may be performed using reactive ion etch (RIE).In some embodiments, the gate height may be provided by material layersfor the gate conductor 14 having a thickness in the range of about 2 nmto about 5 nm, or in the range of about 2 nm to about 3 nm.

Still referring to FIG. 8, a dielectric spacer layer 16 may be blanketdeposited atop the material layer for the gate conductors 14 for theLDMOS devices and the VFET devices. The dielectric spacer layer 16 maybe composed of a low-k dielectric material. In various embodiments, thedielectric spacer layer 16 may be composed of the same material as thedielectric layer 11A that is formed on the drift region 8 in the lateraldevice region 10 and the dielectric layer 11B that provides the firstspacer in the vertical device region 15, as described above withreference to FIG. 5. Therefore, the above description of the dielectriclayer 11A, 11B depicted in FIG. 5 is suitable for the second spacerlayer 16. The second spacer layer 16 may be an oxide. The second spacerlayer 16 may be deposited using a chemical vapor deposition process,such as plasma enhanced chemical vapor deposition (PECVD). In otherexamples, the second spacer layer 16 may be deposited using chemicalsolution deposition or spin on deposition. In some embodiments, theheight of the second spacer layer 16 may be reduced to expose a portionof the cap dielectric 2 that is present on the upper surfaces of the finstructures 5, 10. The height of the second spacer layer 16 may bereduced by etching, such as reactive ion etching (RIE).

FIG. 9 depicting patterning the material layer 14 for the gatestructures 21 a, 21 b for the LDMOS devices and the VFET devices. Thegate structure 21 a, 21 b can be formed using deposition,photolithography and a selective etching process. Specifically, apattern is produced by applying a photoresist to the surface to beetched; exposing the photoresist to a pattern of radiation; and thendeveloping the pattern into the photoresist utilizing a resistdeveloper. Once the patterning of the photoresist is completed, thesections covered by the photoresist are protected while the exposedregions are removed using a selective etching process that removes theunprotected regions. For example, a selective etch process may removethe exposed portions of the second spacer layer 16 and the materiallayer for the gate conductors 14, wherein the remaining portions of thesecond spacer layer 16 and the material layer for the gate conductors 14define the geometry of the gate structures 21 a, 21 b. Although notdepicted in FIG. 9, a dielectric layer may be present filling the spacebetween the gates.

FIG. 10 depicts forming an epitaxial semiconductor material 17 a on theat least one first fin structure 5 in the lateral device region 15 ofthe substrate 1, and forming an epitaxial semiconductor material 17 b onthe at least one second fin structure 10 in the vertical device region20 of the substrate 1. The epitaxial semiconductor material 17 a istypically grown after a dielectric (not depicted) is used to fill inbetween the gates.

The epitaxial semiconductor material 17 a that is formed in the lateraldevice region 15 may provide the source region for the LDMOS device.

The epitaxial semiconductor material 17 b that is formed in the verticaldevice region 20 may provide the second of a source or a drain regionfor the VFETS. For example, when the diffused doped region 9′ is asource region, the epitaxial semiconductor material 17 b provides adrain region formed on the opposing surface, i.e., upper surface of thefin structure 10. In another example, when the diffused doped region 9′is a drain region, the epitaxial semiconductor material 17 b provides asource region is formed on the opposing surface, i.e., upper surface ofthe fin structure 10.

An epitaxial semiconductor material is formed using epitaxial growth.“Epitaxial growth and/or epitaxial deposition” means the growth of asemiconductor material on a deposition surface of a semiconductormaterial, in which the semiconductor material being grown hassubstantially the same crystalline characteristics as the semiconductormaterial of the deposition surface. The term “epitaxial semiconductormaterial” denotes a semiconductor material that has substantially thesame crystalline characteristics as the semiconductor material that ithas been formed on, i.e., epitaxially formed on. In some embodiments,when the chemical reactants are controlled, and the system parametersset correctly, the depositing atoms of an epitaxial deposition processarrive at the deposition surface with sufficient energy to move aroundon the surface and orient themselves to the crystal arrangement of theatoms of the deposition surface. An epitaxial material has substantiallythe same crystalline characteristics as the semiconductor material ofthe deposition surface. For example, an epitaxial film deposited on a{100} crystal surface will take on a {100} orientation. The epitaxialdeposition process may be carried out in the deposition chamber of achemical vapor deposition (CVD) apparatus.

Before, forming the epitaxial semiconductor material 17 a, 17 b, thedielectric cap 2 may be removed to expose the semiconductor surface ofthe fin structures 5, 10 that provides the deposition surface for theepitaxial deposition process. The dielectric cap 2 may be removed usinga selective etch process, such as a wet chemical etch or reactive ionetch. Following removal of the dielectric cap 2, the epitaxialsemiconductor material 17 a, 17 b may be formed.

In some embodiments, the epitaxial semiconductor material 17 a, 17 b maybe composed of silicon. Examples of silicon gas source for epitaxialdeposition of a silicon containing drain region 17 a, 17 b may beselected from the group consisting of hexachlorodisilane (Si₂Cl₆),tetrachlorosilane (SiCl₄), dichlorosilane (Cl₂SiH₂), trichlorosilane(Cl₃SiH), methylsilane ((CH₃)SiH₃), dimethylsilane ((CH₃)₂SiH₂),ethylsilane ((CH₃CH₂)SiH₃), methyldisilane ((CH₃)Si₂H₅),dimethyldisilane ((CH₃)₂Si₂H₄), hexamethyldisilane ((CH₃)₆Si₂) andcombinations thereof. In some embodiments, the epitaxial semiconductormaterial that provides the drain regions 15 a, 15 b may be composed ofgermanium. Examples of germanium gas source for epitaxial deposition maybe selected from the group consisting of germane (GeH₄), digermane(Ge₂H₆), halogermane, dichlorogermane, trichlorogermane,tetrachlorogermane and combinations thereof.

The epitaxial semiconductor material 17 a, 17 b may be doped to a n-typeor p-type conductivity. The dopant for the epitaxial semiconductormaterial 17 a, 17 b may be introduced in-situ during the formation ofthe base material, i.e., epitaxial semiconductor material. The n-typegas dopant source for in-situ doping may include arsine (AsH₃),phosphine (PH₃) and alkylphosphines, such as with the empirical formulaR_(x)PH_((3-x)), where R=methyl, ethyl, propyl or butyl and x=1, 2 or 3.Alkylphosphines include trimethylphosphine ((CH₃)₃P), dimethylphosphine((CH₃)₂PH), triethylphosphine ((CH₃CH₂)₃P) and diethylphosphine((CH₃CH₂)₂PH). The p-type gas dopant source for in-situ doping mayinclude diborane. In other embodiments, the epitaxial semiconductormaterial 17 a, 17 b may also be formed using gas phase doping or ionimplantation.

It is noted that the epitaxial semiconductor material 17 a that isformed in the lateral device region 15 and the epitaxial semiconductormaterial 17 b that is formed in the vertical device region 20 may becomposed of the same composition materials or different compositionsmaterials, and may have the same conductivity type or a differentconductivity type. Block masks may be used to independently process thelateral device region 15 and the vertical device region 20.

In a following process step, an interlevel dielectric layer (not shown)may be formed over the LDMOS device and the VFET device. The interleveldielectric layer may be patterned and etched to provide via openings tothe LDMOS device within the lateral device region 15 and the VFET in thevertical device region 20. The openings may then be filled with anelectrically conductive material, such as a metal, e.g., aluminum,copper, tungsten, titanium, silver, platinum, palladium, tantalum, gold,and combinations thereof, to provide contacts 19 a, 19 b, 19 c.

The contacts to the VFET device in the vertical device region 20 mayinclude a contact to the source region (not shown), a contact to thegate region (not shown), and a contact to the drain region 19 c.

The contacts to the LDMOS device in the lateral device region 15 mayinclude a contact 19 a to the source region, a contact 19 b to the driftregion 8, and a contact to the gate structure (not shown).

FIG. 10 depicts one embodiment of an electrical device that can includea substrate 1 having a lateral device region 10 and a vertical deviceregion 15. The substrate 1 may be a bulk substrate. A firstsemiconductor device 100 a, e.g., LDMOS 100 a, may be present in thelateral device region 10. The first semiconductor device 100A mayinclude a lateral channel portion that has a length L1 that is parallelto an upper surface of the substrate 1 on which the first semiconductordevice is formed. The lateral channel portion may be present in a driftregion 8 of an LDMOS semiconductor device. The lateral device region 15includes at least one first fin structure 5 that is a component of thefirst semiconductor device, e.g., LDMOS. The at least one fin structure5 may provide a vertical channel portion having a length L2 that isperpendicular to the upper surface of the substrate 1. The verticaldevice region 20 includes at least one fin structure 10 that providesthe vertical channel for the VFET. The vertical device region 20 doesnot include a lateral channel.

In some embodiments, the vertical field effect transistor (VFET) devicethat may be present in the vertical device region 29 includes a firstdopant region 9′ for a first of a source region and a drain regionprovided by a doped portion of the substrate 1, and a second dopedregion for a second of the source region and the drain region providedby an second epitaxial semiconductor material 17 b formed on an uppersurface of said second fin structure. A first spacer is provided by afirst dielectric layer 11 a that is present between the gate structureand the first doped region 9′, and a second spacer is provided by adielectric layer 16 b atop the gate conductor 14 b for the gatestructure of the VFET.

In some embodiments, when the first device 100 a is provided by an LDMOSdevice, the LDMOS device includes a drift region 8 provided by a dopedportion of the substrate 1 in the lateral device region 10; and a driftregion gate dielectric 11 a formed on the drift region 8 of thesubstrate 1. The drift region gate dielectric 11 a is the portion of thegate dielectric overlying the lateral length L1 of the channel portionfor the LDMOS device. In one embodiment, the drift region gatedielectric 11 a, 11 c has multiple thickness regions, as depicted inFIG. 6.

Referring to FIG. 10, the drift region gate dielectric 11A is on a samelevel as the dielectric layer 11B that provides the spacer for the VFET.The LDMOS device also includes a fin gate dielectric 12 present on thefin structure 5 that is present in the lateral device region 10. The fingate dielectric 12 is the portion of the gate dielectric that is presenton the vertical channel portion of the LDMOS having the length L2. TheLDMOS gate conductor 14 a is present on the drift region gate dielectric11 a and the fin gate dielectric 12. The LDMOS device that is present inthe lateral device region 15 includes an epitaxial semiconductormaterial 17 a formed on an upper surface of the fin structure 5. Theepitaxial semiconductor material 17 a and the drift region 8 aretypically doped to a first conductivity type, while the fin structure 5that is present in the lateral device region 15 is doped to a secondconductivity type. For example, the epitaxial semiconductor material 17a and the drift region 8 may be doped to an n-type conductivity, whilethe fin structure 5 is doped to a p-type conductivity. In anotherexample, the epitaxial semiconductor material 17 a and the drift region8 may be doped to a p-type conductivity, while the fin structure 5 isdoped to an n-type conductivity.

In one embodiment, the LDMOS has a gate dielectric having a firstthickness, and the VFET has a gate dielectric having a second thickness,wherein the first thickness is greater than the second thickness.

A number of geometries may be employed for the LDMOS device that ispresent in the lateral device region 15. FIGS. 11A and 11B depict oneembodiment of an LDMOS semiconductor device including a gate contact onan active region of the device, in which the drift region gatedielectric 11 a, i.e., drift oxide, has a single thickness. FIG. 11Cdepicts another embodiment of an LDMOS semiconductor device, in whichthe drift region gate dielectric 11 a, i.e., drift oxide, has twothicknesses.

FIGS. 12A and 12B depict one embodiment of an LDMOS semiconductor devicehaving a rectangular contact to the gate region G, in which the gateregion contact is offset from the source and drift region contacts.FIGS. 13A and 13B depict one embodiment of a split gate LDMOSsemiconductor device.

FIGS. 14A-14C depict some embodiments of symmetrical LDMOS semiconductordevices. FIG. 14B depicts one embodiment of a symmetrical LDMOS deviceincluding two source contacts. FIG. 14C depicts one embodiment of asymmetrical LDMOS device including a single source contact. FIGS. 15Aand 15B depict one embodiment of an LDMOS semiconductor device includingan isolation region 21 in the drift region 8. FIGS. 16A and 16B depictyet another embodiment of an LDMOS semiconductor device including anisolation region 21 in the drift region 9, in which the gate contact isoffset from the source contact and the diffusion region contact.

It is noted that each of the embodiments depicted in FIGS. 11A-16B maybe integrated into the process flow described above with reference toFIGS. 1-10.

Having described preferred embodiments of vertical transistorfabrication and devices (which are intended to be illustrative and notlimiting), it is noted that modifications and variations can be made bypersons skilled in the art in light of the above teachings. It istherefore to be understood that changes may be made in the particularembodiments disclosed which are within the scope of the invention asoutlined by the appended claims. Having thus described aspects of theinvention, with the details and particularity required by the patentlaws, what is claimed and desired protected by Letters Patent is setforth in the appended claims.

1.-5. (canceled)
 6. An electrical device comprising: a substrateincluding a lateral device region and a vertical device region; alateral diffusion metal oxide semiconductor (LDMOS) device in thelateral device region, the LDMOS includes at least one first finstructure, wherein a drift region of the LDMOS device has a length thatis parallel to an upper surface of the substrate in which the LDMOSdevice is formed; and a vertical field effect transistor (VFET) devicein the vertical device region, the VFET includes at least one second finstructure, wherein a vertical channel of the VFET has a length that isperpendicular to said upper surface of the substrate, the VFET includinga gate structure that is positioned around the vertical channel, whereinthe VFET further comprises a first of a source region and a drain regionprovided by a doped portion of the substrate in the vertical deviceregion; a second spacer provided by a dielectric layer formed on thedoped portion of the substrate in the vertical device region; thevertical channel region positioned within the at least one second finstructure; a VFET gate structure present on the vertical channel region;and a second of the source region and the drain region provided by ansecond epitaxial semiconductor material formed on an upper surface ofsaid second fin structure. 7.-8. (canceled)
 9. The electrical device ofclaim 6, wherein the VFET gate structure includes a gate dielectric onthe at least one second fin structure, and a gate conductor on the gatedielectric.
 10. The electrical device of claim 6, wherein the LDMOScomprises: a drift region provided by a doped portion of the substratein the lateral device region; a drift region gate dielectric formed onthe drift region of the substrate; wherein the drift region gatedielectric is on a same level as the dielectric layer that provides thesecond spacer; a fin gate dielectric present on the first fin structure;an LDMOS gate structure present on the drift region gate dielectric andthe fin gate dielectric; and a first epitaxial semiconductor materialformed on an upper surface of said first fin structure.
 11. Theelectrical device of claim 10, wherein the drift region gate dielectrichas multiple thickness regions. 12.-20. (canceled)